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thers sessile, sitting on the tips of the petals; follicle round. There are four species. EMBRACERY, is an attempt to corrupt or influence a jury, or any way incline them to be more favourable to the one side than the other, by money, promises, letters, threats, or persuasions; whether the juror, on whom such attempt is made, give verdict or not, or whether the verdict given be true or false, which is punished by fine and imprisonment; and the juror taking money, perpetual infamy, imprisonment for a year, and forfeiture of tenfold the value.
EMBRASURE, in fortification, a hole or aperture in a parapet, through which the cannon are pointed to fire into the moat or field. Embrasures are generally twelve feet distant from one another, every one of them being from six to seven feet wide with out, and about three within: their height above the platform is three feet on that side towards the town, and a foot and a half on the other side towards the field; so that the muzzle may be sunk on occasion, and the piece brought to shoot low.
EMBROCATION, in surgery, an external kind of remedy, which consists in an irrigation of the part affected with some proper liquor, as oils, spirits, &c. by means of a woollen or linen cloth, or a spunge, dipped in the same. The use of embrocation is either to attenuate and dislodge something obstructed underneath the skin, to ease pains, or to irritate the part into more warmth and a quicker sense of feeling. The pumping used in natural baths is properly an embrocation.
EMBROIDERY, a work in gold, or silver, or silk thread, wrought by the needle upon cloth, stuff, or muslin, into various figures. In embroidering stuffs, the work is performed in a kind of loom, because the more the piece is stretched, the easier it is worked. As to muslin, they spread it upon a pattern ready designed; and sometimes, before it is stretched upon the pattern, it is starched to make it more easy to handle. Embroidery on the loom is less tedious than the other, in which, while they work flow. ers, all the threads of the muslin, both lengthwise and breadthwise, must be continually counted; but on the other hand, this last is much richer in points, and susceptible of greater variety. Cloths too much milled are scarce susceptible of this ornament, and in effect we seldom see them embroidered. The thinnest muslins are left for this purpose, and they are embroidered to the greatest perfection in Saxony; in
other parts of Europe, however, they embroider very prettily, and especially in France.
There are several kinds of embroidery, as, 1. Embroidery on the stamp, where the figures are raised and rounded, having cotton or parchment put under them to support them. 2. Low embroidery, where the gold and silver lie low upon the sketch, and are stitched with silk of the same colour, 3. Guimped embroidery: this is performed either in gold or silver; they first make a sketch upon the cloth, then put on cut vellum, and afterwards sew on the gold and silver with silk thread: in this kind of embroidery they often put gold and silver cord, tinsel, and spangles. 4. Embroidery on both sides; that which appears on both sides of the stuff. 5. Plain embroidery, where the figures are flat and even, without cords, spangles, or other ornaments.
EMBROIDERY, no foreign embroidery, on gold or silver brocade, is permitted to be imported into this kingdom on pain of being seized and burned, and a penalty of 100%. for each piece.
EMBRYO, in physiology, the first rudiments of an animal in the womb, before the several members are distinctly formed; after which period it is denominated a fœtus. See FŒTUS and MIDWIFERY.
EMBRYO, in botany. See CORCULUM.
EMERALD. This mineral comes chiefly from Peru; some specimens have been brought from Egypt. Dolomieu found it in the granite of Elba. Hitherto it has been found only crystallized. The primi tive form of its crystals is a regular six-sided prism; and the form of its integrant molecules is a triangular prism, whose sides are squares, and bases equilateral triangles. The most common variety of its crystals is the regular six-sided prism, sometimes with the edges of the prism, or of the bases, or the solid angles, or both wanting, and small faces in their place.
Crystals short; lateral planes smooth, terminal planes rough; colour emerald green of all intensities; internal lustre between 3 and 4; vitreous; fracture small, imperfect, conchoidal, with a concealed foliated fracture, and fourfold cleavage; fragments sharp-edged; transparency 4 to 2; causes double refraction; scratches quartz with difficulty. Specific gravity from 2.600 to 2.7755.
The fossil here described is the occidental emerald, and appears from antique gems to have beer known in the earlier ages, though
at present it comes to us only from South America. Vauquelin found it to contain of silex 64.5, argil 16, glucine 13, oxide of chrome 3.25, lime 1.6, and water 2. The oriental emerald is a green corundum, or resplendent lustre, superior in hardness to every stone but the diamond, and of the specific gravity of 4.
EMERSION, in astronomy, is when any planet that is eclipsed begins to emerge or get out of the shadow of the eclipsing body. It is also used when a star, before hidden by the sun as being too near him, begins to reappear or emerge out of his rays.
EMERSON (WILLIAM), in biography, a late eminent mathematician, was born in June, 1701, at Hurworth, a village about three miles south of Darlington, on the borders of the county of Durham; at least it is certain that he resided here from his childhood. His father, Dudley Emerson, taught a school, and was tolerably proficient in mathematics; and, without his books and instructions, perhaps his son's genius, though eminently fitted for mathematical studies, might never have been unfolded. Beside his father's instructions, our author was assisted in the learned languages by a young clergyman, then curate of Hurworth, who was boarded at his father's house. In the early part of his life he attempted to teach a few scholars; but whether from his concise method, for he was not happy in explaining his ideas, or the warmth of his natural temper, he made no progress in his school; he therefore soon left it off, and, satisfied with a moderate competence left him by his parents, he devoted himself to a studious retirement, which he thus closely pursued, in the same place, through the course of a long life, being mostly very healthy, till towards the latter part of his days, when he was much afflicted with the stone. About the close of the year 1781, being sensible of his approaching dissolution, he disposed of his whole mathematical library to a book seller at York; and on May the 20th, 1782, his lingering and painful disorder put an end to his life, at his native village, being nearly 81 years of age.
Mr. Emerson, in his person, was rather short, but strong and well made, with an open countenance and ruddy complexion, being of a healthy and hardy disposition; he was very singular in his, behaviour, dress, and conversation; his manner and appearance were that of a rude and rather boorish countryman; he was of very plain
conversation, and seemingly rude, commonly mixing oaths in his sentences, though without any ill intention; he had strong good natural mental parts, and could discourse sensibly on any subject, but was always positive and impatient of contradiction; he spent his whole life in close study, and writing books, from the profits of which he redeemed his little patrimony from some original incumbrance; in his dress he was as singular as in every thing else; he possessed commonly but one suit of cloaths at a time, and those very old in their appearance; he seldom used a waistcoat; and his coat he wore open before, except the lower button; and his shirt quite the reverse of one in common use, the hind side turned foremost, to cover his breast, and buttoned close at the collar behind; he wore a kind of rusty coloured wig, without a crooked hair in it, which probably had never been tortured with a comb from the time of its being made; a hat he would make to last him the best part of a life-time, gradually lessening the flaps, bit by bit, as it lost its elasticity and hung down, till little or nothing but the crown remained.
He often walked up to London when he had any book to be published, revising sheet by sheet himself: trusting no eye but his own, was always a favourite maxim with him. In mechanical subjects, he always tried the propositions practically, making all the different parts himself on a small scale; so that his house was filled with all kinds of mechanical instruments, together or disjointed. He would frequently stand up to his middle in water while fishing, a diversion he was remarkably fond of. He used to study incessantly for some time, and then for relaxation take a ramble to any pot ale-house where he could get any body to drink with, and talk to. The late Mr. Montague was very kind to Mr. Emerson, and often visited him, being pleased with his conversation, and used frequently to come to him in the fields where he was working, and accompany him home, but could never persuade him to get into a carriage: on these occasions he would sometimes exclaim, "Damn your whim-wham! I had rather walk." He was a married man, and his wife used to spin on an oldfashioned wheel, of his own making, a drawing of which is given in his "Mechanics."
Mr. Emerson, from his strong, vigorous mind and close application, had acquired deep knowledge of all the branches of mathematics and physics, upon all parts of
which he wrote good treatises, though in a rough and unpolished style and manner. He was not remarkable, however, for genius or discoveries of his own, as his works hardly shew any traces of original invention. He was well skilled in the science of music, the theory of sounds, and the various scales both ancient and modern; but he was a very poor performer, though he could make and repair some instruments, and sometimes went about the country tuning harpsichords.
The following is the list of Mr. Emerson's works, all of them printed in 8vo., excepting his "Mechanics" and his "Increments," in 4to., and his "Navigation" in 12mo. 1. The Doctrine of Fluxions. 2. The Projection of the Sphere, Orthographic, Stereographic, and Gnomonical. 3. The Elements of Trignometry. 4. The Principles of Mechanics. 5. A Treatise of Navigation on the Sea. 6. A Treatise on Arithmetic. 7. A Treatise on Geometry. 8. A Treatise of Algebra, in two books. 9. The Method of Increments. 10. Arithmetic of Infinities, and the Conic Sections, with other Curve Lines. 11. Elements of Optics and Perspective. 12. Astronomy. 13. Mechanics, with Centripetal and Centrifugal Forces.
14. Mechanical Princi
ples of Geography, Navigation, and Dialling. 15. Commentary on the Principia, with the Defence of Newton. 16. Tracts. 17. Miscellanies.
EMERY, a stone of the ruby family, of which three kinds are usually distinguished in commerce; the Spanish, red, and common emery.The first sort is found in the gold mines of Peru, and being judged a kind of marcasite of that rich metal, is prohibited to be exported. The red emery is found in copper mines, and the little there is of it in England comes from Sweden and Denmark. The common emery is taken out of iron mines, and almost the only sort used in England; it is of a brownish colour, bordering a little on red, exceedingly hard, and in consequence difficult to pulverize. The English are the only people who have the art of reducing common emery into powder, and thus send it to their neighbours. Of the powder, the most subtile and impalpable is the best; as to the stone, it should be chosen of a high colour, and as free of the rock as possible.
The consumption of emery is very considerable among the armourers, cutlers, locksiniths, lapidaries, masons, and other mechanics; some of whom use it to polish and burnish iron and steel works; others, to
cut and scallop glass, marble, and precious
EMETIC, a medicine which induces vomiting.
EMETIC tartar, the old name for tartrite of antimony.
EMOLLIENTS. See PHARMACY. EMPETRUM, in botany, heath, a genus of the Dioecia Triandria class and order. Natural order of Erica, Jussieu. Essential character: male, calyx three-parted; corolla three-petalled; stamens long: female, calyx three-parted; corolla three-petalled; styles nine; berry nine-seeded. There are two species; viz. E. album, white-berried heath, and E. nigrum, black-berried heath, crow or crake berry. These are low shrubs, seldom propagated in gardens, unless for variety's sake. They are natives of wild mountains, where the soil is heathy and full of bogs.
EMPIS, in natural history, a genus of insects of the order Diptera. Generic character: mouth with an inflected sucker and proboscis; sucker with a single-valved sheath and three bristles; feelers short, filiform; antennæ setaceous. These minute insects live likewise by sucking out the blood and juices of other animals. There are about 30 species. One of the most common species is the E. livida, which is a brownish fly; the wings are transparent, with dark veins. They are observed in fields and gardens. E. borealis, is of a more slender form than the common window fly, and of a blackish colour, with large, broad, oval wings, of a brown colour, and rufous legs, varied with black.
EMPLASTRUM, in pharmacy, a composition for external use, generally spread upon leather, linen, or some other convenient thing before it is applied. See PHARMACY. The following is a recipe for making the Ladies' Court Plaster: "Dissolve five ounces of isinglass in a pint of water, and having ready a quantity of thin black sarsenet, stretched in a proper frame, apply the solution warm with a brush equally over the surface. This is to be repeated, after it is dry, two or three times." Some give it a coat of gum benzoin dissolved in alcohol; but this is injurious rather than beneficial.
EMPLEURUM, in botany, a genus of the Monoecia Tetrandria class and order. Natural order of Aggregatæ. Rutacea, Jussien. Essential character: male, calyx four-cleft; corolla none: female, calyx fourcleft, inferior; corolla none; stigma cylindric, placed on the lateral toothlet of the
germ; capsule opening on the side; seed one, arilled. There is but one species; viz. E. seriulatum, Cape empleurum. This is a shrub, with wand-like, even branches; leaves like those of a willow, alternate, subpetioled, linear-lanceolate, even above, beneath longitudinally wrinkled; peduncles few-flowered, lateral, much shorter than the leaves; flowers small, most of them male; capsules usually solitary, incurved, with a beak of the same length.
EMULSION, a milky looking fluid caused by an imperfect combination of oil with water by means of mucilage, gluten, &c. All oily farinaceous seeds, as nuts, almonds, linseed, &c. form an emulsion by trituration with water: yolk of egg, which is a natural compound of oil and albumen, makes a similar emulsion.
ENAMELLING. Neri on Glass, with the notes of Merret and Kunckel, afford a variety of good receipts for making enamels, though much still remains to be done in this art. The art is indeed retarded by the considerable advantages the enameller derives from the discovery of any colour uncommonly brilliant, clear, or hard. On this account the artist naturally endeavours to keep his process a secret, as the source of private gain. The principal ingredients of enamel colours are, however, well known.
There are two kinds of enamel ; the opaque and the transparent. Transparent enamels are usually rendered opaque by adding putty, or the white oxide of tin, to them. The basis of all enamels is therefore a perfectly transparent and fusible glass. The oxide of tin renders this a beautiful white, the perfection of which is greater when a small quantity of manganese is likewise added. If the oxide of tin be not sufficient to destroy the transparency of the mixture, it produces a semi-opaque glass, resembling the opal.
Yellow enamel is formed by the addition of oxide of lead or antimony. Kunckel likewise affirms that a beautiful yellow may be obtained from silver.
Red enamel is formed by the oxide of gold, and also by that of iron. The former is the most beautiful, and stands the fire, which the latter does not.
Oxide of copper affords a green, manganese a violet, cobalt a blue, and iron a very fine black. A mixture of these enamels produces a great variety of intermediate colours, according to their nature and proportion. In this branch of the art the coloured enamels are sometimes mixed with
each other, and sometimes the oxides are mixed before they are added to the vitrious bases.
The enameller who is provided with a set of good colours is very far from being in a situation to practise the art, unless he be skilled in the methods of applying them, and the nature of the grounds upon which they are to be laid. Many of the metals are too fusible to be enamelled, and most of them are corroded by the action of the fused glass. For this reason none of the metals are used but gold, silver, and copper. Platina has indeed been used; but of its effects and habitudes with enamel very little can be said, for want of a sufficient number of experiments,
The purest gold, of 24 carats, is calculated to produce the best effect with enamel. 1. Because it entirely preserves the metallic brilliancy, without undergoing any oxidation in the fire. 2. Being less fusible, it will admit of a more refractory, and consequently a harder and more beautiful enamel. It is not usual, however, to enamel on finer gold than 22 carats; and the operation would be very defective, if a coarser kind than that of 18 carats were used. For in this case more alkali must be added to the enamel to render it more fusible, and this addition would, at the same time, render it softer and less brilliant.
Rejecting all these exceptions, the following description may be taken, by way of example, of fixing a transparent blue enamel upon gold of 22 carats.
The artist begins his operation by breaking his enamel into small pieces in a steel mortar, and afterwards pulverizing it in a mortar of agate. He is careful to add wa ter in this part of the process, which prevents the splinters of glass from flying about. There are no means of explaining the point at which the trituration ought to be given up, as this can be learned only by experi ence. Some enamels require to be very finely triturated; but others may be used in the form of a coarse powder. As soon as he apprehends that his enamel is sufficiently pounded, he washes it by agitation in very clear water, and pouring off the fluid as it becomes turbid. This process, which is made for carrying off dust and every other impurity from the enamel, is continued until the water comes off as clear as it was poured on.
The workman puts his enamel thus prepared into a white earthen or china saucer, with water poured on it to the depth of
about one-tenth of an inch.
He afterwards takes up the enamel with an iron spatula as equally as possible. As the enamel here spoken off is transparent, it is usual to ornament the gold with rose work, or other kinds of work, calculated to produce a good effect through the enamel.
The thickness of this first layer depends entirely upon its colour: delicate colours in general require that it should have no great thickness.
The moist enamel being thus placed, is dried by applying a very clean half-worn linen cloth to it, which must be very carefully done to avoid removing the enamel by the action of wiping.
In this state the piece is ready for the fire. If it be enamelled on both sides, it is placed upon a tile, or iron plate, hollowed out in such a manner that the uncovered edges of the piece alone are in contact with the support. But if it be enamelled on one side only, it is simply laid upon the plate, or upon a tile. Two things, however, require to be attended to. 1. If the work be very small, or not capable of being enamelled on the opposite side, the iron plate must be perfectly flat, in order that the work may not bend when softened by heat. 2. If the work be of considerable size, it is always counter-enamelled, if possible; that is to say, an enamel is applied on the back surface, in order to counteract the effect which the other coating of glass might produce on the soft metal when it came to contract by cooling.
The enameller's furnace is square, and built of bricks bedded in an earth proper for the purpose. It may be considered as consisting of two parts, the lower part which receives a muffle resting on the floor of the furnace, and open on both sides.
The upper part of the furnace consists of a fire place, rather larger and longer than the dimensions of the muffle. The fire place contains the muffle, and must surround it on all sides, except at the bottom, The charcoal is put in at a door above the mutile, which is closed as soon as the fire is lighted. A chimney proceeds from the summit of the furnace with a moderate aperture, which may be closed at the pleasure of the artist, by applying a cast iron plate to it. This furnace differs from that of the assayer, in the circumstance that it is supplied with air through the muffle itself: for if the draught were beneath the muffle, the heat would be too strong, and could not be stopped when requisite.
As soon as the fire is lighted, and the muffle has acquired the requisite degree of ignition, the charcoal is disposed towards the lower part of the muffle in such a manner as that it shall not fall upon the work, which is then conveyed into the muffle with the greatest care upon the plate of iron or earthern-ware, which is taken out by long spring pincers. The work is placed as near as possible at the farther extremity of the muffle; and as soon as the artist perceives a commencement of fusion, he turns it round with great delicacy, in order that the fusion may be very uniform. And as soon as he perceives that the fusion has entirely taken place, he instantly removes it out of the furnace for the fusion of gold happens so very near to that of the enamel, that the neglect of a few seconds might be. attended with considerable loss.
When the work is cooled, a second coat of enamel is applied in the same manner as the first, if necessary. This and the same cautious management of the fire are to be repeated for every additional coat of enamel the nature of the work may demand.
As soon as the number of coatings are sufficient, it becomes necessary to give an even surface to the enamel, which though polished by the fire, is nevertheless irregu lar. This is done with a fine grained Lancashire file, and water. As the file wears smooth, sand is used. Much precaution and address are required in this part of the work, not only because it is easy to make the enamel separate in splinters from the metal, but likewise because the colour would not be uniform if it were to be ground thinner at one part than at another.
The deep scratches of the file are in the next place taken cut by rubbing the surface with a piece of deal wood and fine sand and water. A polish is then given by a second ignition. This polish, however, is frequently insufficient, and not as perfectly uniform as the delicacy of the work may require.
The substance used by the enamellers as a polishing material is known by the name of rotten-stone, which is prepared by pounding, washing, decanting off the turbid water, suffering the fine suspended particles to subside from this water, and lastly levigating it upon a glass plate.
The work is then cemented to a square piece of wood, with a mixture of resin and brickdust, and by this means fixed in a vice.
The first operation of polishing is made